Global computer networks, such as the Internet and the World Wide Web are commonly used to exchange digitized audio, video, graphics and text between end-user terminals. Moreover, networking technology has now advanced to the point where telephony over these platforms is also practical. In the case of the Internet, voice data input from a microphone at the transmitting terminal is digitally packetized per the Internet Protocol (IP) and transmitted via the Internet to the receiving terminal where it is unpacked and reconverted back into voice. While having many advantages, computer networked-based telephony is still subject to a number of disadvantages vis a vis traditional telephony.
In IP telephony, only packets carrying active speech samples are transmitted to save bandwidth. Consequently, the data reaching the receiving terminal is discontinuous, resulting in audible “clicks” and “pops,” in the speaker or headset. Another undesirable effect at the receiving end is echo caused by feedback between the speaker and the microphone at the sender's terminal. An echo suppressor can be used to alleviate this effect, however, echo suppression often results in modulated noise and a “dead-set” phenomenon at the receiving end.
Given the increasing popularity of computer network-based telephony, techniques are required to reduce or eliminate echo without introducing the “dead-set” phenomenon. Further, the problem of clicks and pops caused by gaps in transmission of active data must also be addressed. In other words, techniques are required for improving echo suppressor performance and receiving terminal performance in light of discontinuous signal transmission.